Method and apparatus to provide necessary output torque reserve by selection of hybrid range state and input speed for a hybrid powertrain system

ABSTRACT

A method for controlling a powertrain system includes determining a current transmission operating range state and engine state, determining at least one potential transmission operating range state and engine state, providing at least one operator torque request, determining preferability factors associated with the current transmission operating range state and engine state, and potential transmission operating range states and engine states, wherein determining preferability factors associated with potential transmission operating range states includes assigning biasing costs to operator torque requests which reside within a pre-determined range of possible operator torque requests for at least two of the potential transmission operating range states, preferentially weighting the preferability factors for the current transmission operating range state and engine state, and selectively commanding changing the transmission operating range state and engine state based upon stheaid preferability factors and the operator torque request.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/985,232 filed on Nov. 4, 2007, which is hereby incorporated herein byreference.

TECHNICAL FIELD

This disclosure relates generally to control systems forelectro-mechanical transmissions.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Known powertrain architectures include torque-generative devices,including internal combustion engines and electric machines, whichtransmit torque through a transmission device to an output member. Oneexemplary powertrain includes a two-mode, compound-split,electro-mechanical transmission which utilizes an input member forreceiving motive torque from a prime mover power source, preferably aninternal combustion engine, and an output member. The output member canbe operatively connected to a driveline for a motor vehicle fortransmitting tractive torque thereto. Electric machines, operative asmotors or generators, generate a torque input to the transmission,independently of a torque input from the internal combustion engine. Theelectric machines may transform vehicle kinetic energy, transmittedthrough the vehicle driveline, to electrical energy that is storable inan electrical energy storage device. A control system monitors variousinputs from the vehicle and the operator and provides operationalcontrol of the powertrain, including controlling transmission operatingstate and gear shifting, controlling the torque-generative devices, andregulating the electrical power interchange among the electrical energystorage device and the electric machines to manage outputs of thetransmission, including torque and rotational speed.

SUMMARY

A powertrain system in a motorized vehicle has an accelerator pedal andincludes an engine coupled to an electro-mechanical transmissionselectively operative in one of a plurality of transmission operatingrange states and one of a plurality of engine states. A method forcontrolling the powertrain system includes determining a currenttransmission operating range state and engine state, determining atleast one potential transmission operating range state and engine state,providing at least one operator torque request, determiningpreferability factors associated with the current transmission operatingrange state and engine state, and potential transmission operating rangestates and engine states, wherein determining preferability factorsassociated with potential transmission operating range states includesassigning biasing costs to operator torque requests which reside withina pre-determined range of possible operator torque requests for at leasttwo of the potential transmission operating range states, preferentiallyweighting the preferability factors for the current transmissionoperating range state and engine state, and selectively commandingchanging the transmission operating range state and engine state basedupon stheaid preferability factors and the operator torque request.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an exemplary powertrain, in accordancewith the present disclosure;

FIG. 2 is a schematic diagram of an exemplary architecture for a controlsystem and powertrain, in accordance with the present disclosure;

FIG. 3 shows an arrangement of a first plurality of preferabilityfactors relating to a method, in accordance with the present disclosure;

FIG. 4 illustrates a combination of a plurality of preferability factorsin accordance with the present disclosure;

FIG. 5A provides a graphical representation of a stabilization ofchanges of operating range of an electro-mechanical hybrid transmission,in accordance with the present disclosure;

FIG. 5B shows an alternate graphical representation of a stabilizationof changes of operating range of an electro-mechanical hybridtransmission, in accordance with the present disclosure;

FIG. 6 depicts an architecture useful in carrying out execution of achange of operating range of an electro-mechanical hybrid transmission,in accordance with the present disclosure;

FIG. 7 shows a path taken by the transmission input speed over thecourse of a change from one potential transmission operating range stateto another, in accordance with the present disclosure;

FIG. 8 illustrates variation in transmission input speed values as afunction of time for various potential operating range states of anelectro-mechanical hybrid transmission, in accordance with the presentdisclosure;

FIG. 9 shows differences in rpm values between different transmissioninput speed values at a selected point in time between various potentialoperating range states of an electro-mechanical hybrid transmission, inaccordance with the present disclosure;

FIG. 10 shows a profile of how input speeds for an electro-mechanicalhybrid transmission vary at a change in mode during resetting of afilter, in accordance with the present disclosure;

FIG. 11 illustrates one biasing cost function useful in biasing thepreferability of a potential transmission operating range state for agiven operator torque request, in accordance with the presentdisclosure;

FIG. 12 is one embodiment of a representation of the difference overtime between an operator torque request and a desirable transmissiontorque output for an exemplary transmission operating range state, inaccordance with the present disclosure;

FIG. 13 is a graphical definition of the space in which a search engineselects values for evaluation of torque outputs for continuouslyvariable transmission modes, in accordance with the present disclosure;

FIG. 14 diagrammatically illustrates the utility of a switch inpermitting selection of either a first Torque Reserve range size, asecond Torque Reserve range size, and a Torque Reserve of zero, inaccordance with the present disclosure;

FIGS. 15 and 16 collectively illustrate a comparison of the size ofranges of operator torque requests over which the biasing cost functionwhich establishes the Torque Reserve for different operating modes of amotorized vehicle equipped with a transmission, in accordance with thepresent disclosure; and

FIG. 17 shows a biasing cost function in the absence of a TorqueReserve, in accordance with the present disclosure.

DETAILED DESCRIPTION

Referring now to the drawings, wherein the showings are for the purposeof illustrating certain exemplary embodiments only and not for thepurpose of limiting the same, FIG. 1 shows an exemplaryelectro-mechanical hybrid powertrain. The exemplary electro-mechanicalhybrid powertrain shown in FIG. 1 comprises a two-mode, compound-split,electro-mechanical hybrid transmission 10 operatively connected to anengine 14, and first and second electric machines (‘MG-A’) 56 and(‘MG-B’) 72. The engine 14 and first and second electric machines 56 and72 each generate power which can be transmitted to the transmission 10.The power generated by the engine 14 and the first and second electricmachines 56 and 72 and transmitted to the transmission 10 is describedin terms of input torques, referred to herein as T_(I), T_(A), and T_(B)respectively, and speed, referred to herein as N_(I), N_(A), and N_(B),respectively.

In one embodiment, the exemplary engine 14 comprises a multi-cylinderinternal combustion engine which is selectively operative in severalstates to transmit torque to the transmission 10 via an input shaft 12,and can be either a spark-ignition or a compression-ignition engine. Theengine 14 includes a crankshaft (not shown) operatively coupled to theinput shaft 12 of the transmission 10. A rotational speed sensor 11 ispreferably present to monitor rotational speed of the input shaft 12.Power output from the engine 14, comprising rotational speed and outputtorque, can differ from the input speed, N_(I), and the input torque,T_(I), to the transmission 10 due to torque-consuming components beingpresent on or in operative mechanical contact with the input shaft 12between the engine 14 and the transmission 10, e.g., a hydraulic pump(not shown) and/or a torque management device (not shown).

In one embodiment the exemplary transmission 10 comprises threeplanetary-gear sets 24, 26 and 28, and four selectively-engageabletorque-transmitting devices, i.e., clutches C1 70, C2 62, C3 73, and C475. As used herein, clutches refer to any type of friction torquetransfer device including single or compound plate clutches or packs,band clutches, and brakes, for example. A hydraulic control circuit 42,preferably controlled by a transmission control module (hereafter ‘TCM’)17, is operative to control clutch states. In one embodiment, clutchesC2 62 and C4 75 preferably comprise hydraulically-applied rotatingfriction clutches. In one embodiment, clutches C1 70 and C3 73preferably comprise hydraulically-controlled stationary devices that canbe selectively grounded to a transmission case 68. In a preferredembodiment, each of the clutches C1 70, C2 62, C3 73, and C4 75 ispreferably hydraulically applied, selectively receiving pressurizedhydraulic fluid via the hydraulic control circuit 42.

In one embodiment, the first and second electric machines 56 and 72preferably comprise three-phase AC machines, each including a stator(not shown) and a rotor (not shown), and respective resolvers 80 and 82.The motor stator for each machine is grounded to an outer portion of thetransmission case 68, and includes a stator core with electricalwindings extending therefrom. The rotor for the first electric machine56 is supported on a hub plate gear that is operatively attached toshaft 60 via the second planetary gear set 26. The rotor for the secondelectric machine 72 is fixedly attached to a sleeve shaft hub 66.

Each of the resolvers 80 and 82 preferably comprises a variablereluctance device including a resolver stator (not shown) and a resolverrotor (not shown). The resolvers 80 and 82 are appropriately positionedand assembled on respective ones of the first and second electricmachines 56 and 72. Stators of respective ones of the resolvers 80 and82 are operatively connected to one of the stators for the first andsecond electric machines 56 and 72. The resolver rotors are operativelyconnected to the rotor for the corresponding first and second electricmachines 56 and 72. Each of the resolvers 80 and 82 is signally andoperatively connected to a transmission power inverter control module(hereafter ‘TPIM’) 19, and each senses and monitors rotational positionof the resolver rotor relative to the resolver stator, thus monitoringrotational position of respective ones of first and second electricmachines 56 and 72. Additionally, the signals output from the resolvers80 and 82 are interpreted to provide the rotational speeds for first andsecond electric machines 56 and 72, i.e., N_(A) and N_(B), respectively.

The transmission 10 includes an output member 64, e.g. a shaft, which isoperably connected to a driveline 90 for a vehicle (not shown), toprovide output power, e.g., to vehicle wheels 93, one of which is shownin FIG. 1. The output power is characterized in terms of an outputrotational speed, N_(O) and an output torque, T_(O). A transmissionoutput speed sensor 84 monitors rotational speed and rotationaldirection of the output member 64. Each of the vehicle wheels 93, ispreferably equipped with a sensor 94 adapted to monitor wheel speed,V_(SS-WHL,) the output of which is monitored by a control module of adistributed control module system described with respect to FIG. 2, todetermine vehicle speed, and absolute and relative wheel speeds forbraking control, traction control, and vehicle acceleration management.

The input torques from the engine 14 and the first and second electricmachines 56 and 72 (T_(I), T_(A), and T_(B) respectively) are generatedas a result of energy conversion from fuel or electrical potentialstored in an electrical energy storage device (hereafter ‘ESD’) 74. ESD74 is high voltage DC-coupled to the TPIM 19 via DC transfer conductors27. The transfer conductors 27 include a contactor switch 38. When thecontactor switch 38 is closed, under normal operation, electric currentcan flow between the ESD 74 and the TPIM 19. When the contactor switch38 is opened electric current flow between the ESD 74 and the TPIM 19 isinterrupted. The TPIM 19 transmits electrical power to and from thefirst electric machine 56 by transfer conductors 29, and the TPIM 19similarly transmits electrical power to and from the second electricmachine 72 by transfer conductors 31, in response to torque commands forthe first and second electric machines 56 and 72 to achieve the inputtorques T_(A) and T_(B). Electrical current is transmitted to and fromthe ESD 74 in accordance with commands provided to the TPIM which derivefrom such factors as including operator torque requests, currentoperating conditions and states, and such commands determine whether theESD 74 is being charged, discharged or is in stasis at any giveninstant.

The TPIM 19 includes the pair of power inverters (not shown) andrespective motor control modules (not shown) configured to receive thetorque commands and control inverter states therefrom for providingmotor drive or regeneration functionality to achieve the input torquesT_(A) and T_(B). The power inverters comprise known complementarythree-phase power electronics devices, and each includes a plurality ofinsulated gate bipolar transistors (not shown) for converting DC powerfrom the ESD 74 to AC power for powering respective ones of the firstand second electric machines 56 and 72, by switching at highfrequencies. The insulated gate bipolar transistors form a switch modepower supply configured to receive control commands. There is typicallyone pair of insulated gate bipolar transistors for each phase of each ofthe three-phase electric machines. States of the insulated gate bipolartransistors are controlled to provide motor drive mechanical powergeneration or electric power regeneration functionality. The three-phaseinverters receive or supply DC electric power via DC transfer conductors27 and transform it to or from three-phase AC power, which is conductedto or from the first and second electric machines 56 and 72 foroperation as motors or generators via transfer conductors 29 and 31,depending on commands received which are typically based on factorswhich include current operating state and operator torque demand.

FIG. 2 is a schematic block diagram of the distributed control modulesystem. The elements described hereinafter comprise a subset of anoverall vehicle control architecture, and provide coordinated systemcontrol of the exemplary hybrid powertrain described in FIG. 1. Thedistributed control module system synthesizes pertinent information andinputs, and executes algorithms to control various actuators to achievecontrol objectives, including objectives related to fuel economy,emissions, performance, drivability, and protection of hardware,including batteries of ESD 74 and the first and second electric machines56 and 72. The distributed control module system includes an enginecontrol module (hereafter ‘ECM’) 23, the TCM 17, a battery pack controlmodule (hereafter ‘BPCM’) 21, and the TPIM 19. A hybrid control module(hereafter ‘HCP’) 5 provides supervisory control and coordination of theECM 23, the TCM 17, the BPCM 21, and the TPIM 19. A user interface(‘UI’) 13 is operatively connected to a plurality of devices throughwhich a vehicle operator may selectively control or direct operation ofthe electro-mechanical hybrid powertrain. The devices present in UI 13typically include an accelerator pedal 113 (‘AP’) from which an operatortorque request is determined, an operator brake pedal 112 (‘BP’), atransmission gear selector 114 (‘PRNDL’), and a vehicle speed cruisecontrol (not shown). The transmission gear selector 114 may have adiscrete number of operator-selectable positions, including therotational direction of the output member 64 to enable one of a forwardand a reverse direction.

The aforementioned control modules communicate with other controlmodules, sensors, and actuators via a local area network (hereafter‘LAN’) bus 6. The LAN bus 6 allows for structured communication ofstates of operating parameters and actuator command signals between thevarious control modules. The specific communication protocol utilized isapplication-specific. The LAN bus 6 and appropriate protocols providefor robust messaging and multi-control module interfacing between theaforementioned control modules, and other control modules providingfunctionality such as antilock braking, traction control, and vehiclestability. Multiple communications buses may be used to improvecommunications speed and provide some level of signal redundancy andintegrity. Communication between individual control modules can also beeffected using a direct link, e.g., a serial peripheral interface(‘SPI’) bus (not shown).

The HCP 5 provides supervisory control of the powertrain, serving tocoordinate operation of the ECM 23, TCM 17, TPIM 19, and BPCM 21. Basedupon various input signals from the user interface 13 and thepowertrain, including the ESD 74, the HCP 5 generates various commands,including: the operator torque request (‘T_(O) _(—) _(REQ)’), acommanded output torque (‘T_(CMD)’) to the driveline 90, an engine inputtorque command, clutch torques for the torque-transfer clutches C1 70,C2 62, C3 73, C4 75 of the transmission 10; and the torque commands forthe first and second electric machines 56 and 72, respectively. The TCM17 is operatively connected to the hydraulic control circuit 42 andprovides various functions including monitoring various pressure sensingdevices (not shown) and generating and communicating control signals tovarious solenoids (not shown) thereby controlling pressure switches andcontrol valves contained within the hydraulic control circuit 42.

The ECM 23 is operatively connected to the engine 14, and functions toacquire data from sensors and control actuators of the engine 14 over aplurality of discrete lines, shown for simplicity as an aggregatebi-directional interface cable 35. The ECM 23 receives the engine inputtorque command from the HCP 5. The ECM 23 determines the actual engineinput torque, T_(I), provided to the transmission 10 at that point intime based upon monitored engine speed and load, which is communicatedto the HCP 5. The ECM 23 monitors input from the rotational speed sensor11 to determine the engine input speed to the input shaft 12, whichtranslates to the transmission input speed, N_(I). The ECM 23 monitorsinputs from sensors (not shown) to determine states of other engineoperating parameters which may include without limitation: a manifoldpressure, engine coolant temperature, throttle position, ambient airtemperature, and ambient pressure. The engine load can be determined,for example, from the manifold pressure, or alternatively, frommonitoring operator input to the accelerator pedal 113. The ECM 23generates and communicates command signals to control engine actuators,which may include without limitation actuators such as: fuel injectors,ignition modules, and throttle control modules, none of which are shown.

The TCM 17 is operatively connected to the transmission 10 and monitorsinputs from sensors (not shown) to determine states of transmissionoperating parameters. The TCM 17 generates and communicates commandsignals to control the transmission 10, including controlling thehydraulic circuit 42. Inputs from the TCM 17 to the HCP 5 includeestimated clutch torques for each of the clutches, i.e., C1 70, C2 62,C3 73, and C4 75, and rotational output speed, N_(O), of the outputmember 64. Other actuators and sensors may be used to provide additionalinformation from the TCM 17 to the HCP 5 for control purposes. The TCM17 monitors inputs from pressure switches (not shown) and selectivelyactuates pressure control solenoids (not shown) and shift solenoids (notshown) of the hydraulic circuit 42 to selectively actuate the variousclutches C1 70, C2 62, C3 73, and C4 75 to achieve various transmissionoperating range states, as described hereinbelow.

The BPCM 21 is signally connected to sensors (not shown) to monitor theESD 74, including states of electrical current and voltage parameters,to provide information indicative of parametric states of the batteriesof the ESD 74 to the HCP 5. The parametric states of the batteriespreferably include battery state-of-charge, battery voltage, batterytemperature, and available battery power, referred to as a range P_(BAT)_(—) _(MIN) to P_(BAT) _(—) _(MAX).

Each of the control modules ECM 23, TCM 17, TPIM 19 and BPCM 21 ispreferably a general-purpose digital computer comprising amicroprocessor or central processing unit, storage mediums comprisingread only memory (‘ROM’), random access memory (‘RAM’), electricallyprogrammable read only memory (‘EPROM’), a high speed clock, analog todigital (‘A/D’) and digital to analog (‘D/A’) circuitry, andinput/output circuitry and devices (‘I/O’) and appropriate signalconditioning and buffer circuitry. Each of the control modules has a setof control algorithms, comprising resident program instructions andcalibrations stored in one of the storage mediums and executed toprovide the respective functions of each computer. Information transferbetween the control modules is preferably accomplished using the LAN bus6 and serial peripheral interface buses. The control algorithms areexecuted during preset loop cycles such that each algorithm is executedat least once each loop cycle. Algorithms stored in the non-volatilememory devices are executed by one of the central processing units tomonitor inputs from the sensing devices and execute control anddiagnostic routines to control operation of the actuators, using presetcalibrations. Loop cycles are preferably executed at regular intervals,for example at each 3.125, 6.25, 12.5, 25 and 100 milliseconds duringongoing operation of the powertrain. However, any interval between about2 milliseconds and about 300 milliseconds may be selected.Alternatively, algorithms may be executed in response to the occurrenceof any selected event.

The exemplary powertrain shown in reference to FIG. 1 is capable ofselectively operating in any of several operating range states that canbe described in terms of an engine state comprising one of an engine onstate (‘ON’) and an engine off state (‘OFF’), and a transmission statecomprising a plurality of fixed gears and continuously variableoperating modes, described with reference to Table 1, below.

TABLE 1 Engine Transmission Operating Applied Description State RangeState Clutches M1_Eng_Off OFF EVT Mode 1 C1 70 M1_Eng_On ON EVT Mode 1C1 70 G1 ON Fixed Gear Ratio 1 C1 70 C4 75 G2 ON Fixed Gear Ratio 2 C170 C2 62 M2_Eng_Off OFF EVT Mode 2 C2 62 M2_Eng_On ON EVT Mode 2 C2 62G3 ON Fixed Gear Ratio 3 C2 62 C4 75 G4 ON Fixed Gear Ratio 4 C2 62 C373

Each of the transmission operating range states is described in thetable and indicates which of the specific clutches C1 70, C2 62, C3 73,and C4 75 are applied for each of the operating range states. As anexample, a first continuously variable mode, i.e., EVT Mode 1, or M1, isselected by applying clutch C1 70 only in order to “ground” the outergear member of the third planetary gear set 28. The engine state can beone of ON (‘M1_Eng_On’) or OFF (‘M1_Eng_Off’). A second continuouslyvariable mode, i.e., EVT Mode 2, or M2, is selected by applying clutchC2 62 only to connect the shaft 60 to the carrier of the third planetarygear set 28. The engine state can be one of ON (‘M2_Eng_On’) or OFF(‘M2_Eng_Off’). For purposes of this description, when the engine stateis OFF, the engine input speed is equal to zero revolutions per minute(‘RPM’), i.e., the engine crankshaft is not rotating. A fixed gearoperation provides a fixed ratio operation of input-to-output speed ofthe transmission 10, i.e., N_(I)/N_(O), is achieved. For example, afirst fixed gear operation (‘G1’) is selected by applying clutches C1 70and C4 75. A second fixed gear operation (‘G2’) is selected by applyingclutches C1 70 and C2 62. A third fixed gear operation (‘G3’) isselected by applying clutches C2 62 and C4 75. A fourth fixed gearoperation (‘G4’) is selected by applying clutches C2 62 and C3 73. Thefixed ratio operation of input-to-output speed increases with increasedfixed gear operation due to decreased gear ratios in the planetary gears24, 26, and 28. The rotational speeds of the first and second electricmachines 56 and 72, N_(A) and N_(B) respectively, are dependent oninternal rotation of the mechanism as defined by the clutching and areproportional to the input speed measured at the input shaft 12.

In response to operator input via the accelerator pedal 113 and brakepedal 112 as captured by the user interface 13, the HCP 5 and one ormore of the other control modules determine the commanded output torque,T_(CMD), intended to meet the operator torque request, T_(O) _(—)_(REQ), to be executed at the output member 64 and transmitted to thedriveline 90. Resultant vehicle acceleration is affected by otherfactors including, e.g., road load, road grade, and vehicle mass. Theoperating range state is determined for the transmission 10 based uponinputs which include a variety of operating characteristics of thepowertrain. These include the operator torque request communicatedthrough the accelerator pedal 113 and brake pedal 112 to the userinterface 13

In some embodiments, the operating range state may be predicated on apowertrain torque demand caused by a command to operate the first andsecond electric machines 56 and 72 in an electrical energy generatingmode or in a torque generating mode. In some embodiments, the operatingrange state can be determined by an optimization algorithm or routinewhich determines a preferential selection of the operating range statebased upon inputs which may include: operator demand for power; batterystate-of-charge; and operating efficiencies of the engine 14 and thefirst and second electric machines 56, 72. The control system managestorque inputs from the engine 14 and the first and second electricmachines 56 and 72 based upon pre-selected outcome criteria embedded inthe executed selection routine, and system operation is controlledthereby to effectively manage resources commensurate with desired levelsof ESD state-of-charge and fuel delivery. Moreover, operation can bedetermined, including over-riding of any desired feature(s), based upondetection of a fault in one or more components or sub-systems. The HCP 5monitors the torque-generative devices, and determines the power outputfrom the transmission 10 required to achieve the output torque necessaryto meet the operator torque request. The ESD 74 and the first and secondelectric machines 56 and 72 are electrically-operatively coupled forpower flow therebetween. Furthermore, the engine 14, the first andsecond electric machines 56 and 72, and the electro-mechanicaltransmission 10 are mechanically-operatively coupled to transmit powertherebetween to generate a power flow to the output member 64.

Given various operating conditions possible for a motorized vehicleequipped with an electro-mechanical hybrid transmission, which includevaried environmental and road conditions such as road grade and operatortorque demands, it is generally possible for an electro-mechanicalhybrid transmission to be usefully operatively engaged potentially inmore than one transmission operating range state, including such rangestates specified in Table I, at a given time during its operation.Moreover, it may be true that for every change in road grade, throttleopening, and brake pedal depression that a motorized vehicle comprisingan electro-mechanical hybrid transmission experiences during the courseof its typical travel, differing transmission operating range state andengine states of the engine may at any time be viewed as beingadvantageous in consideration of an overall balance between such factorsincluding fuel economy, required torque output of the transmission, andstate-of-charge of the ESD 74. At any one instant in time, a particulartransmission operating range state and engine state may be desirable,advantageous or preferred, while at subsequent instants in time othertransmission operating range state and engine states may be desirable,advantageous or preferred, with the result being that over even arelatively short time span of operation such as, for example, fiveminutes, conditions making dozens or more desirable, advantageous, orpreferred transmission operating range state and engine states existduring such time span. However, this disclosure provides that alteringthe transmission operating range state and engine state in response toeach and every single change in operating conditions encountered is notnecessarily desirable in a motorized vehicle having anelectro-mechanical hybrid transmission.

According to one embodiment of this disclosure, FIG. 3 shows a firstplurality of numerical values, each of which represents a preferabilityfactor for each of the potential operating range states of anelectro-mechanical hybrid transmission, and potential engine states forthe engine, including the operating range states and engine statesspecified in Table I. In FIG. 3, the designations M1 and M2 refer tomode 1 and mode 2 of the electro-mechanical hybrid transmission. Thedesignations G1, G2, G3, and G4 refer to gear 1, gear 2, gear 3, andgear 4, respectively, and HEOff refers to the engine state, which enginestate is either engine-on or engine-off. In one embodiment of thisdisclosure, any one or more such preferability factors may bearbitrarily assigned. In another embodiment, any one or more of suchpreferability factors may comprise an output generated as a result ofany algorithmic or other data processing method which has as an input orbasis any information provided by any one or more sensors disposed atany location on a motorized vehicle equipped with such anelectro-mechanical hybrid transmission, or disposed on, at, or near anyportion of its drive train where data may be acquired. Such sensors mayinclude without limitation: a wheel speed sensor 94, an output speedsensor 84, and a rotational speed sensor 11.

It is desired that the preferability factors provided for each of thetransmission operating range states and engine state shown in FIG. 3 aremaintained in association with their respective transmission operatingrange state and engine state, and according to one embodiment of thisdisclosure such preferability factors are set forth in an array, asshown in FIG. 3. This arrangement is not a strict requirement, but is ofconvenience when performing a method according to this disclosure, asshown and described in relation to FIG. 4.

This disclosure also provides a plurality of numerical values, each ofwhich is associated with one of the possible operating range states andengine states of an electro-mechanical hybrid transmission at anyselected point in time while in service in a motorized vehicle, such asduring operation while a vehicle is traveling on a road surface, whichplurality may be referred to as current operating range state values.Preferred embodiments include a numerical value associated with theengine state. This second plurality of numerical values are shownarranged in an array in FIG. 4 labeled as “current operating rangefactors” which includes numerical values for both the transmissionoperating range state and the engine state.

FIG. 4 illustrates how the numerical values of the first plurality ofpreferability factors from FIG. 3 may be combined with the secondplurality of preferability factors from the current operating rangestate and engine state. In one embodiment, the combination is made bysumming the numerical values from each corresponding operating rangestate and engine state in each array, to arrive at a third array thatcomprises preferability factors for each possible transmission operatingrange state and engine state, which is labeled “new desired operatingrange factors”. As used herein, a desired operating range state refersto a transmission operating range state or engine state that is, for onereason or another, generally relating to drivability, but may relate toengine economy, emissions or battery life, more desirable than thecurrent transmission operating range state and/or engine state. Thenumerical values present in the third array may be compared to oneanother, and in one embodiment the lowest numerical value present in thethird array represents the transmission operating range state or enginestate which is to be selected or evaluated for selection as a basis uponwhich to make a change in operating state of the electro-mechanicalhybrid transmission while a motorized vehicle containing same is inoperation. For example, in the third array in FIG. 4, the lowestnumerical value is 7, corresponding to mode 1 operation of theelectro-mechanical hybrid transmission, whereas the current operatingrange state for the transmission is mode 2, evidenced by the zero in thecurrent operating range array being the lowest numerical value. In oneillustrative, non-limiting exemplary embodiment, a signal would be sentto a shift execution module embedded in the TCM 17, suggesting a changeof transmission operating range state from mode 2 to mode 1, which maybe effected by the TCM. In alternate embodiments, the TCM may beprovided with additional decision-making data and algorithms to eitheraccept and execute a suggested command change resulting from a processaccording to this disclosure, or it may deny such execution, based onother factors programmed into the TCM 17 which can be arbitrary in oneembodiment, and in other embodiments are based on the output of one ormore algorithms having inputs provided by on-board vehicle sensors. Inone embodiment of the disclosure, the TCM 17 provides current operatingrange factors, which may be in the same format that the numerical valuesfor the second plurality of preferability factors are in. In otherembodiments, the TCM 17 provides current operating range factors in anyformat different than that which the numerical values relating to thesecond plurality of preferability factors are in.

In another embodiment, the first plurality of preferability factorsdescribed in reference to FIG. 3 may be combined with an alternativeplurality of preferability factors, which are depicted in the arraylabeled as the “desired operating range factors” (which includenumerical values for both the transmission operating range state and theengine state) in FIG. 4, to arrive at a third array comprising a set ofpreferability factors which are considered the “new desired operatingrange factors.” The preferability factors comprising the desiredoperating range factors may be an output generated as a result of anyalgorithm or other data processing method of information provided by anyone or more sensors disposed at any location on a motorized vehicleequipped with such an electro-mechanical hybrid transmission, ordisposed on, at, or near any portion of its drive train where data maybe acquired. Such sensors include without limitation: a wheel speedsensor 94, an output speed sensor 84, and a rotational speed sensor 11.In another embodiment, the first plurality of preferability factorsdescribed in reference to FIG. 3 may be combined with both thepreferability factors from the current operating range factors and thedesired operating range factors to arrive at a third array comprisingnew desired operating range factors.

In general, one or more of the preferability factors among the desiredoperating range factors will change over time, in response to changingoperating conditions encountered by a motorized vehicle equipped with anelectro-mechanical hybrid transmission, and the value of these factorsmay either increase or decrease during vehicle operation. For example,when an operator makes a torque request upon encountering an uphillgrade while traveling at a low speed, the preferability factorassociated with gear 1 operation may be caused to decrease in value inresponse thereto. Similarly, when the vehicle operator makes a brakingtorque request upon encountering an downhill grade while traveling at aconstant speed, the preferability factor associated with gear 1operation may be caused to increase substantially in value so thatselection of the gear 1 operating range is essentially precluded.

In FIG. 4, the numerical values in the arrays comprising the currentoperating range factors and the desired operating range factors areidentical only for illustrative purposes, and in practice the numericalvalues present in these sets of preferability factors may differ fromone another. For embodiments in which the first plurality ofpreferability factors from FIG. 3 are combined with those of the desiredoperating range factors, a third array comprising preferability factorsfor a new desired operating range factors are provided, at least one ofwhich factors are subsequently provided to a shift control module whichmay be embedded in the TCM 17. For instances in which the shift controlmodule orders the execution of a change in transmission operating rangestate, engine state, or both, the preferability factors comprising thenew desired operating range factors are communicated as an input to aprocess of this disclosure as the desired operating range factors in asubsequent iteration of a process as herein described, as it isdesirable in such embodiments to repeatedly perform a method asdescribed herein at any time interval desired or selected, which may beany interval between about 2 milliseconds and about 300 milliseconds,including all intervals and ranges of intervals therebetween.

In preferred combinations of preferability factors according to thedisclosure, it is desirable to only combine preferability factors oflike kind with one another, i.e., preferability factors relating to M1may only be combined with other preferability factors which relate toM1, G2 with G2, and so forth. Although combination of arrays, each ofwhich comprise a plurality of preferability factors according to oneembodiment of this disclosure has been shown and described as involvingthe summation of such arrays, and selecting the least value present inan array as a value for consideration in making a change in theoperating range of an electro-mechanical hybrid transmission, thepresent disclosure also includes embodiments in which the selectioncriteria is to choose the largest numerical value. In other embodiments,the combination of two or more arrays may include subtraction, division,or multiplication of the numerical values corresponding to eachoperating range present in the arrays so combined, to provide that oneof the values emerges as unique or differentiable from the remainingvalues present as a result of such combination, each value representinga relative preferability of the engine state or transmission rangestate. Selection is then made basis the highest or lowest numericalvalue present, or any other differentiable numerical attribute, in eachof such embodiments. For cases where two or more preferability factorspresent in a set or array which results from a combination ofpreferability factors as provided herein are identical ornon-differentiable from one another, the selection of a transmissionoperating range from such non-differentiable values may be arbitrary, ormay be set to any default selection desired.

In one embodiment of the disclosure, the numerical values of the firstplurality of preferability factors in the array shown in FIG. 3 may beselected to be of a size sufficient to provide a biasing effect whencombined with numerical values present in either the desired operatingrange factors or current operating range factors as described inreference to FIG. 4. For convenience according to one embodiment, setsof such preferability factors from FIG. 3 may be provided and arrangedin a matrix, as shown in Table II and Table III below:

TABLE II Bias offset matrix for stabilization of current operating rangeDesired Range M1 M2 G1 G2 G3 G4 HEOff Current M1 0 0.5 A 0.5 0.5 0.5 0.5Range M2 0.5 0 0.1 0.1 0.2 0.5 0.2 G1 0.5 0.5 0 0.5 0.3 0.5 0.5 G2 0.30.1 0.5 0 0.5 0.3 0.2 G3 0.5 0.2 0.3 0.5 0 0.5 0.5 G4 0.5 0.5 0.5 0.20.5 0 0.5 HEOff 0.5 0.5 0.5 0.5 0.5 0.5 0Thus, a plurality of preferability factors for the current operatingrange factors may be provided from such matrix. Under such anarrangement, if the current operating range of the electro-mechanicalhybrid transmission is mode 1, then numerical values from the first roware chosen as the numerical values for the array to be used in acombination of arrays as described herein. Arrays for the desiredoperating range factors may be selected from a matrix such as that shownin Table III, as representative of preferability factor valuesassociated with the desired operating range state of theelectro-mechanical hybrid transmission and engine state.

TABLE III Bias offset matrix for stabilization of previously selecteddesired operating range Desired Range M1 M2 G1 G2 G3 G4 HEOff PreviouslyM1 0 0.5 B 0.5 0.5 0.5 0.5 Selected M2 0.5 0 0.1 0.1 0.2 0.5 0.2 DesiredG1 0.5 0.5 0 0.5 0.3 0.5 0.5 Range G2 0.3 0.1 0.5 0 0.5 0.3 0.2 G3 0.50.2 0.3 0.5 0 0.5 0.5 G4 0.5 0.5 0.5 0.2 0.5 0 0.5 HEOff 0.5 0.5 0.5 0.50.5 0.5 0

When combining arrays comprising current operating range factors anddesirable operating range factors described in reference to FIG. 4 witha plurality of preferability factors as provided in reference to FIG. 3according to this disclosure, the net effect is to stabilize theshifting of the transmission to both the desired operating range and thecurrent operating range by inclusion of the preferability factorsprovided according to FIG. 3. Through judicious selection of the valuesin Tables II and III above, an unexpected benefit arises in that it ispossible to select values which prohibit specific changes in operatingrange states of an electro-mechanical hybrid transmission. For example,a change in operating range from mode 2 to gear 4 may be permitted,whereas a change in operating range from mode 2 to gear 3 may beforbidden, the choices of which changes to permit or forbid being incontrol of the user of a method herein by their judicious selection ofnumerical values for the preferability factors. In general, it isdesirable to avoid selecting non-allowed range states, whether based onoutput speed of the transmission or any other criteria selected by auser. In one embodiment, different potential input speeds for mode 1 andmode 2 operation of the transmission are considered over time inproviding corresponding numerical values for these states in the firstplurality of numerical values, independent of the desired transmissionoperating range state. According to one embodiment, a selection processinvolves consideration only of the input speed associated with thedesired transmission operating state selected. In one preferredembodiment, the numerical value representative of the currenttransmission operating range state has a bias of zero. In otherembodiments, the numerical value representative of the currenttransmission operating range state has a relatively small bias, and maybe either positive or negative. Although shown as positive numericalvalues, a preferability factor according to the disclosure may benegative, since the net result of a process herein which combines thedifferent preferability factors for the result specified dependsgenerally on their relative magnitudes with respect to one another.

The net effect of the stabilization of shifting events or changes ofoperating range of an electro-mechanical hybrid transmission accordingto this disclosure is illustrated in FIG. 5A, which uses power loss asits ordinate; however, other units of ordinate may be employed asdesired. In FIG. 5A the power loss associated with vehicle operation ingear 1 over time of varying operating conditions is shown by the dottedwavy line. As this power loss varies along the abscissa of time labeledas mode 1, it may be possible for other operating range states of theelectro-mechanical hybrid transmission to be employed to advantage withrespect to fuel economy, battery state-of-charge, total torque output,etc. However, given typical wide variance in torque demands over time byan operator, a plurality of shifting or transmission mode changes wouldadversely impact drivability of a vehicle so equipped. Hence, by thepresent incorporation of bias, by consideration of the preferabilityfactors described, the power loss associated with vehicle operation ingear 1 over time of varying operating conditions may be moved upwards onthe ordinate scale, to the corresponding solid wavy line, the amount ofwhich bias is represented by the sum of factors A and B from the firstrow in Table II and Table III respectively. The result of this withreference to FIG. 5A is that the transmission operating range remains inmode 1 until the power loss associated with operating in that mode, plusthe bias amount, exceeds the power loss of operating in anotheroperating range state, in this case gear 1, at which point a change inoperating range state is effected, with the power loss throughout thedepicted time interval following the path marked by solid circles.Accordingly, situations where excessive operating range state changes ofan electro-mechanical hybrid transmission occur, are maintained at anydesirable level, dictated by the preferability factors chosen, which canmean their minimization, as well as substantial or complete elimination.This result is also depicted in FIG. 5B, which shows the transmissiondesired operating range state as ordinate, depicting the removal of whatwould have been deemed as an undesirable operating range state changefor some end-use applications of a vehicle equipped with anelectro-mechanical hybrid transmission according to the disclosure.

In one embodiment, the matrices, arrays, or other arrangements ofpreferability factors as described herein are caused to be present in oraccessible to a microprocessor, in hard or soft memory, and thecombinations described herein are preferably carried out using such aprocessing device, which then issues an output to a TCM 17 that itselfemploys such output as an input in its own decision-making process.However, any arrangement of the preferability factors in memory which isconvenient for computing purposes may be employed, in addition to suchmatrices or arrays as herein described. Individual preferability factorsmay relate to, or be based upon any number of potential variablesrelating to vehicle operation, and include without limitation variablesrelating to energy usage, drivability, fuel economy, tailpipe emissions,and battery state-of-charge, with information concerning such variablesbeing provided in one embodiment, by sensors. In other embodiments, thepreferability factors may be derived from or based on losses in theentire mechanical drive system, including losses due to belts, pulleys,valves, chains, losses in the electrical system, heat losses, electricalmachine power losses, internal battery power loses, or any otherparasitic loss in a vehicle system, taken either alone, or incombination with any one or more other loss or losses.

FIG. 6 depicts an architecture including a microprocessor, which iscapable of carrying out execution of a change of operating range stateof an electro-mechanical hybrid transmission according to one embodimentof the disclosure. FIG. 6 shows microprocessor MP, having inputs of thecurrent desired range preferability factors, and the preferabilityfactors described in reference to FIG. 3. The microprocessor has anoutput, which is inputted to a transmission control module, TCM 17,which itself provides feedback to the microprocessor in the form of aplurality of current operating range state preferability factors. TheTCM 17 is capable of providing a suggested shift execution command tothe transmission 10.

Operation of a vehicle equipped with an electro-mechanical hybridtransmission as herein described (including functionally-equivalentdevices) also includes the transmission input speed, N_(I), which itselfis subject to change as vehicle operating conditions encountered duringtravel of a motorized vehicle vary. After undergoing a change inoperating conditions, it is true that in many cases a differenttransmission operating range state may become more desirably employedthan the present or current transmission operating range state. Ingeneral, the transmission input speed N_(I) are different for differenttransmission operating range states possible when the motorized vehicleis traveling at the same given speed, when different operating modes ortransmission operating states are contemplated as being employed asalternate operative modalities for operating at a same given speed.Accordingly, a change in transmission operating state and/or enginestate is desirably accompanied by a change in transmission input speedN_(I).

FIG. 7 illustrates graphically one example of how the transmission inputspeed N_(I) may vary over time when a vehicle equipped with anelectro-mechanical hybrid transmission as herein described undergoes anexemplary change in operating range state from M1 to M2. The N_(I) forM1 represents the current N_(I) when the current transmission operatingrange state is M1. G2 N_(I) and M2 N_(I) represent the selected(desired) N_(I) for the corresponding transmission operating rangestates. Since a direct change of operating range state from M1 to M2 isforbidden, the transmission must first pass through G2. During such atransition, the necessary transmission input speed N_(I) is seen tofirst decrease when going from M1 to G2, then to increase slightly overtime during brief operation in G2, after which a steep increase in N_(I)is experienced in achieving M2 operation. Therefore, the path or “trip”that the transmission input speed N_(I) is seen to go through is givenby:(M1N _(I) −G2N _(I))+(M2N _(I) −G2N _(I))  [1]in which M1 N_(I) is the transmission input speed for transmission M1operation; G2 N_(I) is the transmission input speed for transmission G2operation, M2 N_(I) is the transmission input speed for transmission M2operation, and G2 N_(I) is the transmission input speed for transmissionG2 operation. By weighting the direction of change of N_(I), the total“cost” of the trip that the transmission input speed is seen to gothrough can be provided by a calculation of the type:TC=[(M1N _(I) −G2N _(I))*a+(M2N _(I) −G2N _(I))*b]*x  [2]in which the “*” character indicates a multiplication operation, and aand b are constants in which a is used for negative changes in N_(I) andin which b is used for positive changes in N_(I). In alternateembodiments, a and b are varying parameters which are a function of thecorresponding distance of the N_(I) trip or the corresponding desiredtransmission operating range state. The variable x, a trip-directionweighting constant, is a subjective value which may be set or determinedby the vehicle engineers. The determination of x takes into accountwhether a potential change in transmission operating range state firstrequires a shift up followed by a shift down, or whether it firstrequires a shift down, followed by a shift up, as shown in FIG. 7. Ifthe required sequence is shift down, then shift up, then x is set to asubjectively-determined value c. If the required sequence is shift upthen shift down, the x is set to a subjectively-determined value d. Forthe case illustrated in FIG. 7, the formula for determining TC is:TC=[(M1N _(I) −G2N _(I))*a+(M2N _(I) −G2N _(I))*b]*c  [3]By analogous arithmetic a trip costing factor (TC) may be readilyprovided for every potential change in transmission operating rangestate and engine state by consideration of the trip that the N_(I) mustpass for a given potential change in transmission operating range stateand engine state at any point in time of the vehicle travel. Althoughthe changes in N_(I) shown in FIG. 7 follow a straight-line path forpurposes of illustration, in actual operation the changes in N_(I) mayalso follow curved paths during all or a portion of the transition,wherein the paths may be either concave-up or concave-down. As shown asoccurring at different points in time in FIG. 7, the calculation of theN_(I) values for M1, which in this example is the origin of the trip isthat of the monitored current N_(I) value, and the calculation of N_(I)values for G2 and M2 operation, which represent the intermediate andfinal destinations of the trip, may be conducted simultaneously.

FIG. 8 graphically illustrates how selected values of N_(I) may varyover time for each transmission operating range state shown during theoperation of a motorized vehicle equipped with an electro-mechanicalhybrid transmission as herein described. The current N_(I) profilerepresents the monitored current N_(I) values, which in this example iswhen the current transmission operating range state is M1. In oneembodiment, the selected N_(I) values (which may in alternateembodiments be desired N_(I) values or required N_(I) values) at variouspoints in time are arbitrarily selected to yield the curves shown. Inother embodiments the selected N_(I) values at various points in timeare based on the output of one or more algorithms having inputs providedby on-board vehicle sensors, which after manipulation such as by amicroprocessor may provide curves similar or different to those shown inFIG. 8. Importantly, as shown in FIG. 9, for each point in time T_(x)under consideration, there is associated with each of such curves asingle point, which may be used as a basis for calculating thedifferences in rpm, labeled “Δ rpm” which differences in rpm are usefulin determining a trip costing factor associated with every potentialchange in transmission operating range state for any desired point intime. While rpm is used herein to exemplify one implementation, otherrotational speed metrics are equally applicable. In one embodiment, theΔ rpm values may be conveniently set forth in an array as in Table IVbelow:

TABLE IV rpm difference values associated with potential changes intransmission operating range states. M1 M2 G1 G2 G3 G4 HEOff 0 Δ rpm 3 Δrpm 1 Δ rpm 3 Δ rpm 4 Δ rpm 5 Δ rpm 6 Δ rpm 2wherein the rpm differences associated with M2 involves the rpmdifference M1 to G2 and G2 to M2 as earlier described. The M1 N_(I)value used for the Δ rpm calculation is that of the current M1 N_(I)value and not that of the selected M1 N_(I) value. The values for the Δrpm in Table IV are exemplary of those encountered when the transmissionis presently in M1 operation, as the value of the Δ rpm for M1 is zero,which has a biasing effect that tends to maintain the transmissionoperating range state in M1, thus stabilizing the transmission operatingrange state with respect to M1 operation. In one embodiment, the valuesfor the Δ rpm associated with each potential change in transmissionoperating range state, such as those provided in Table IV, are each nextmultiplied by the trip direction weighting constants a, b, c, d (whichin alternate embodiments may be varying parameters which are a functionof the corresponding distance of the trip, Δ rpm, or correspondingdesired range) from the equation defining TC above for each associatedpotential change in transmission operating range state, to arrive at anew array comprising a plurality of Trips Costing factors (TC)representing preferability factors for each of the transmissionoperating range states that are effectively based on the input speedtrip or profile associated with each potential change in operating rangestate of the transmission, of which the values in Table V are providedfor exemplary purposes and are non-limiting of this disclosure:

TABLE V preferability factors based on transmission input speed N_(I)trip M1 M2 G1 G2 G3 G4 HEOff 0 0.6 0.3 0.4 0.5 0.7 0.8

The preferability factors based on the input speed trip or profile(“transmission input speed trip preferability factors”) associated witheach potential operating range state of the transmission as set forth inTable V may be combined as herein specified with other sets ofpreferability factors, including one or more sets of preferabilityfactors shown in and described with reference to FIG. 4 towardsgeneration of new desired operating range factors. The selected N_(I)values at various points in time as shown in FIG. 8 may be based on theoutput of one or more algorithms carried out in a microprocessor havingone or more inputs provided by on-board vehicle sensors, includingwithout limitation sensors mentioned herein. In some embodiments,transmission input speeds N_(I) for M1 operation and M2 operation areprovided at selected intervals with regard to the desired operatingrange state of the transmission. In one embodiment, the N_(I) value forM1 is selected by a microprocessor which searches and selects an N_(I)value that is associated with the least power loss, which in thisembodiment may serve as, or as a basis for determining the preferabilityfactor for M1 operation from FIG. 3. At or at about the same time, theN_(I) value for M2 operation is selected by a microprocessor whichsearches and selects an N_(I) value that is associated with the leastpower loss, which in this embodiment may serve as, or as a basis fordetermining the preferability factor for M2 operation from FIG. 3.Slight changes in operating conditions can substantially alter thepreferability factors, and could result in transmission operation thatwould attempt to change gears or modes too frequently, and the biasingor weighting of the preferability factors as herein described alleviatesundesirably frequent shifting. For embodiments in which N_(I) values forM1 and M2 are continuously provided at short time intervals on the orderof milliseconds in response to changes in vehicle operating conditions,given that slight changes in operating conditions can substantiallyalter the preferability factors, it occurs that there may be widefluctuations in the N_(I) values for M1 and M2 from one time interval tothe next. Changing operating range state for every instance that adriving condition changed slightly would result essentially in atransmission which was nearly constantly attempting to change gears ormodes, and the biasing or weighting of the preferability factors asherein described alleviates undesirably frequent shifting. Followinggeneration of new desired operating range factors and selection of thedesired operating range, the N_(I) values for the desired operatingrange are evaluated for selection and it is frequently the case that theN_(I) values may vary substantially from one interval to the next. It isaccordingly desirable to “filter” the N_(I) values, to remove noise,which noise comprises values that are very high above or below anaverage N_(I) value owing to instantaneous fluctuation in the N_(I)values during one or more short time intervals. In one embodiment, N_(I)values for both M1 operation, M2 operation and neutral are filtered,even though the values of only one of M1 or M2 are actually to be usedat a given point in time, i.e., the system continuously provides N_(I)values for both M1 and M2 operation. In such embodiment, while inputspeeds N_(I) for M1 or M2 operation are provided continuously or atselected intervals, only the input speed N_(I) associated with thedesired mode (either M1 or M2) is used for creating a desiredtransmission input speed profile based on current vehicle operatingconditions. After selection of a desired range state is made, theselected N_(I) values for M1 and M2 are filtered to reduce noise, whilefiltering, when the desired range changes reset the filter of the modeof the desired range that it is transitioning to, in order that theinitial output value is equivalent to the input value, as shown in FIG.10. The suggested N_(I) values depicted therein will eventually be usedto create a profile of desired input speeds based on what range isdesired. For example, when M1 is selected as the desired range, N_(I) M1is used as the desired N_(I) profile, as soon as M2 becomes desired theprofile will switch to suggested N_(I) M2. This selective resetting isdone so that when the system switches from one profile to another, thenon-filtered suggested N_(I) is used as the initial value. Whenfiltering the suggested input speeds for noise reduction, only thesuggested input speed of the desired mode is filtered. This allows thesuggested input speed to reset when its mode is chosen.

One consideration of operating a motorized vehicle that is equipped withan electro-mechanical hybrid transmission as described herein, is thatthe operator of such a motorized vehicle will at different times makedifferent torque requests from the drivetrain (such as by depressing theaccelerator or brake pedal). However, in many instances of operatortorque requests, the drivetrain and/or braking system may be incapableof delivering the amount of torque requested by the operator, i.e., thebrake or accelerator pedal may be depressed beyond the point at whichthe system capabilities to deliver the requested torque can befulfilled.

For different engine operating points in potential operating rangestates of the transmission, given the same operator torque request, thedifferences between the operator-requested torque and the drivetraincapabilities typically differ from one another. In one embodiment ofthis disclosure, the difference between the amount of torque requestedby the operator at a given point in time and the torque that isdeliverable by the system when operating at a potential engine operatingpoint is considered for each of the engine operating points, to generatea plurality of torque difference values for each of the engine operatingpoints at substantially the time that the operator makes a torquerequest. In one embodiment a biasing “cost” value is assigned to each ofthe torque difference values in proportion to the magnitude by which thedeliverable torque for a given engine operating point in a potentialtransmission operating range state falls short with respect to that ofthe operator torque request. Such biasing cost values generally reflecta lower degree of desirability for engine operating points having higherbiasing costs associated with them for a given operator torque request,when such biasing costs are compared with one another and used as abasis in evaluating which engine operating point is most suitable ordesirable for a given operator torque request at a particular point intime of the vehicle operation. In one embodiment, the sum of allcomponents representing power losses for various drivetrain componentsand this bias cost (comprising the total power loss) for each potentialengine operating point at the torque deliverable that is nearest to thatrequested by the vehicle operator are compared with one another, withthat potential engine operating point having the least total power losswhen operated at the torque nearest that of the operator request beingselected as the desired engine operating point.

FIG. 11 shows a cost function useful in providing biasing costsindicating a component of preferability of a potential engine operatingpoint and transmission operating range state, which is dependent on themagnitude of a torque request made by the operator. The exemplarydefinition of a biasing cost graph in FIG. 11 is a generally-paraboliccost profile, having as its abscissa the operator torque request. Such abiasing cost profile may be determined by any function desired,selected, or created by the vehicle engineers, and accordingly affordsan opportunity to include a subjective aspect in the determination ofpreferability of different engine operating points and potentialtransmission operating range states. Function types useful in thisregard include without limitation: hyperbolic functions, linearfunctions, continuous functions, non-continuous functions, constantfunctions, smooth-curved functions, circular functions, ovoid functions,and any combinations comprising any of the foregoing, either alone ormathematically combined with one another, over any range of operatortorque request values desired or selected. Thus, in one embodiment,criteria used in the determination of which engine operating point andtransmission operating range state is most desirable for a givenoperator torque request at any selected point in time of the travel of avehicle having a drivetrain as herein described is not necessarily boundto the most efficient operation of the motorized vehicle in terms offuel economy, power output, drivability, etc.

For each engine operating point and potential transmission operatingrange state, there exists a minimum output torque (T_(O) Min) and amaximum output torque (T_(O) Max) that the drivetrain system is capableof delivering. The maximum output torque is generally applicable towardsvehicle acceleration and includes such components as torque inputted tothe transmission by the engine and torque supplied to the transmissionby the electric machines. The minimum output torque is generallyapplicable towards vehicle deceleration, and includes such components asbraking torque provided during regenerative braking, including caseswhen the charging of a battery on-board the vehicle is accomplished,more or less, by one or more electric machines functioning in theircapacity as electrical generators.

With respect to FIG. 11, which represents a single engine operatingpoint in a potential transmission operating range state, it is clearthat for a substantial range of possible operator torque request valuesresiding between T_(O) Min and T_(O) Max, there is no biasing costassociated therewith, i.e., the value of the function represented by thedotted line is zero. As the operator torque request approaches orexceeds the T_(O) Max value, however, the cost associated with theoperator torque request is given by the ordinate value along the dottedline curve corresponding to the operator torque request. Other potentialtransmission operating range states may have the same, similarly-shaped,or differently-shaped functions associated with them, as desired.

In one embodiment, if the operator torque request is within a rangebetween T_(O) Min and T_(O) Max where the biasing cost functionrepresented by the dashed line curve in FIG. 11 is constant, in thiscase at zero, there is no biasing cost assigned for the particularengine operating point in the operating range state under considerationat levels of operator torque request residing within this range. Whenthe operator torque request is for a torque that is greater than T_(O)Max, the function determining the biasing costs associated with thetorque request is represented by the dashed line in FIG. 11. Thisbiasing cost may thus comprise a subjective component in addition to theobjective costs associated with power losses in the determination of theengine operating point selection and the first plurality of numericalvalues shown in FIG. 3. Thus, in one embodiment, an operator torquerequest which only slightly exceeds that of T_(O) Max, by, for example,10 Newton-meters, will be assigned a biasing cost which is less than thebiasing cost which would be assigned to an operator torque request whichexceeds that of T_(O) Max by more than 10 Newton-meters.

Table VI below is exemplary of one way to express costs associated withthe difference between a vehicle operator torque request and the maximumtorque deliverable by the drivetrain system for an exemplary potentialtransmission operating range state, wherein Δ N*m is the differencevalue in Newton-meters and kW is the cost, expressed in kilowatts inthis example; however any other convenient units, or no units, may beused. Such an array may be stored in computer memory and accessed by amicroprocessor, on an as-needed basis.

TABLE VI Costs assigned for different torque requests for a potentialtransmission operating range state Δ N * m 0 10 100 1000 kW 0 20 50180,000

An alternative representation of the biasing cost associated with apotential transmission operating range state is shown in FIG. 12. InFIG. 12, the value x represents the difference between the amount oftorque requested by the operator and that torque output which isdesirable (“Desirable T_(O)”) for a potential transmission operatingrange state, as but one example. The Desirable T_(O) is that amount oftorque that is closest to the operator torque request that is availablebased on the output torque limits (T_(O) Max and T_(O) Min) of theselected engine operating points and the Torque Reserve for theparticular potential transmission operating range state underconsideration. The quantity x, which is a torque difference value (ΔN*m), varies, depending on which potential transmission operating stateis under consideration, for the same operator torque request at a samegiven point in time of the vehicle operation. Comparison of x values fordifferent potential transmission operating range states given the sameoperator torque request enables selection of that potential transmissionoperating range state having the least x value, in one embodiment. Inanother embodiment, a biasing cost (weighting factor) may be assigned tothe potential transmission operating range state having the least xvalue, which is combined with the sum of all components representingpower losses for various drivetrain components, to arrive at a sum totalpower loss which may then be used as a criteria for selecting aparticular potential transmission operating range state over others.

By providing a function having any desired features, including withoutlimitation those features illustrated by the biasing costs curve in FIG.11, it is possible to assign a biasing cost to a given operator torquerequest for particular instances even when the torque requested in anoperator torque request is below the maximum system torque output. Thisis illustrated by an operator torque request having the magnitude atpoint Q in FIG. 11, which is below the T_(O) Max, yet there isnevertheless a cost assigned for this potential transmission operatingrange state and operator torque request. Such a provision of costing (orbiasing) operator torque requests allows establishment of a TorqueReserve over the range of operator torque requests which reside betweenTo Max and the operator torque request having the highest magnitude oftorque for which no biasing cost is assigned over a range between T_(O)Min and T_(O) Max. The provision of a range of operator torque requestscomprising such a Torque Reserve effectively biases the preferability ofthe transmission control system against selecting system actuatoroperating points and transmission operating range states having a T_(O)Max which is greater than, yet near to, an operator torque request in anamount that is proportional to the difference between the operatortorque request and the T_(O) Max for the particular engine operatingpoint in a transmission operating range state under consideration.Instead of biasing to select system actuator operating points which canproduce the highest T_(O) Max and lowest T_(O) Min, including the TorqueReserve has the effect of decreasing the bias criteria point T_(O) Maxto T_(O) Max subtracted by the Torque Reserve. This will not only effectthe operator torque requests which exceed the maximum deliverable outputtorque, but also the operator torque requests that are less than andnear the maximum deliverable output torque. This results in improveddrivability of the motorized vehicle by reducing the tendency of thetransmission system to cause multiple shifting events or mode changeswhen an operator torque request has a magnitude that is near the maximumdeliverable for the transmission operating range state that is currentlyselected, i.e., currently under utilization. In embodiments whichfollow, no Torque Reserve is present.

Moreover, when an operator torque request exceeds T_(O) Max (or is lessthan T_(O) Min) for cases where a method according to this disclosurewhich so uses biasing costs is not employed, information relating to theamount by which an operator torque request exceeds T_(O) Max (or is lessthan T_(O) Min) is lost due to the fact that the total power lossevaluation is based on the deliverable output torque which is limited byT_(O) Max and T_(O) Min. Proceeding in accordance with a method of thisdisclosure and obtaining a biasing cost value for an operator torquerequest which exceeds T_(O) Max (or is less than T_(O) Min) providesinformation relative to the amount by which such a torque request is inexcess of T_(O) Max, and this information is incorporated into theoverall selection process concerning which engine operating point andpotential transmission operating state will be selected. In oneembodiment, this information effectively biases a search engine embeddedwithin software and/or hardware useful for providing the plurality ofnumerical values shown in FIG. 3 to locate an engine operating pointwithin each potential transmission operating range state that biasestowards providing the greatest value of T_(O) Max (least value of T_(O)Min). In one embodiment, the biasing costs associated with the operatortorque request for each of the potential operating range states of thetransmission substantially at the time an operator makes a torquerequest during vehicle operation are but one component used indetermining a first plurality of numerical values as shown in FIG. 3.

In one embodiment, the calculation of each of the numerical valuespresent in the first plurality of numerical values shown in FIG. 3include components relating to objective power losses such as: enginepower loss, battery power loss, electrical machine power loss, andtransmission power loss. Another embodiment provides additional penaltycosts, including costs for exceeding the battery power limits, enginetorque limits, electric machine torque limits, and other subjectivecosts desired which may include biasing costs associated with the outputtorque request as herein described. Also included are the componentsgenerated as the result of an iterative data processing method that inone embodiment employs a microprocessor-based search engine.

In the case of continuously variable operating mode range states, searchengine suitable for such a method employs, for each potentialtransmission operating range state, a space that is defined as shown inFIG. 13 by the region on the coordinate axes bounded by P_(I) Min, P_(I)Max, N_(I) Min, and N_(I) Max, wherein P_(I) represents power inputtedto the electro-mechanical hybrid transmission and N_(I) is the sametransmission input speed. The search engine selects, either randomly oraccording to any desired algorithm, an N_(I) and P_(I) pair present inthe space S and calculates a T_(O) Min, T_(O) Max, and total power lossassociated with the N_(I) and P_(I) pair chosen, based on drivetrainsystem component power losses and operating constraints, whichconstraints are either inherent in the system, or imposed by vehicleengineers. Repetition of this method for a large number of differentN_(I) and P_(I) pairs provides a plurality of different T_(O) Min, T_(O)Max, and total power loss values for a given potential transmissionoperating range state. The method is repeated for each potentialtransmission operating range state and a plurality of T_(O) Min, T_(O)Max, and total power loss values are generated in the space S of and foreach potential transmission operating range state and N_(I) and P_(I)pairs provided.

From such plurality of different T_(O) Min and T_(O) Max values sogenerated by a search engine for a given potential transmissionoperating range state, the N_(I) and P_(I) pair having the highest T_(O)Max value associated with each potential transmission operating rangestate is biased to be selected as the preferred N_(I) and P_(I), toreduce biasing costs associated with the output torque request in FIG.11, which is one of the multiple components in the total power loss,when an operator torque request is greater than the plurality ofdifferent T_(O) Max values generated. For cases in which an operatortorque request is less than the plurality of different T_(O) Mingenerated, the N_(I) and P_(I) pair associated with the lowest T_(O) Minvalue is biased to be selected as the preferred N_(I) and P_(I) toreduce biasing costs associated with the output torque request in FIG.11, which is one of the multiple components in the total power loss forthe particular potential transmission operating range state underconsideration. The hybrid Engine-Off state can be considered ascontinuously variable modes with the N_(I) and P_(I) as being zero;thus, T_(O) Min, T_(O) Max, and the total power loss are determinedwithout the need for a search procedure.

In the case of Fixed Gear range states, a search engine suitable forsuch a method employs, for each potential transmission operating rangestate, a space that is defined by the region on the coordinate axesbounded by T_(I) Min, and T_(I) Max, wherein T_(I) represents torqueinputted to the electro-mechanical hybrid transmission where thetransmission input speed is predetermined by the hardware parameter ofpotential transmission operating range state. The search engine selects,either randomly or according to any desired algorithm, a T_(I) presentin the search range and calculates a T_(O) Min and T_(O) Max and TotalPower Loss associated with the T_(I) chosen, based on drivetrain systemcomponent power losses and operating constraints, which constraints areeither inherent in the system, or imposed by vehicle engineers.Repetition of this method for a large number of different T_(I) providesa plurality of different T_(O) Min and T_(O) Max and Total Power Lossvalues for a given potential transmission operating range state. Themethod is repeated for each potential transmission operating range stateand a plurality of T_(O) Min and T_(O) Max and Total Power Loss aregenerated in the search range of and for each potential transmissionoperating range state and T_(I) is provided.

From such plurality of different T_(O) Min and T_(O) Max values sogenerated by a search engine for a given potential transmissionoperating range state, the T_(I) having the highest T_(O) Max valueassociated with each potential transmission operating range state isbiased to be selected as the preferred T_(I), when an operator torquerequest is greater than the plurality of different T_(O) Max generated.This reduces biasing costs associated with the output torque request inFIG. 11, which is one of the components in the total power loss for theparticular potential transmission operating range state underconsideration. For cases in which an operator torque request is lessthan the plurality of different T_(O) Min generated, the T_(I)associated with the lowest T_(O) Min value is biased to be selected asthe preferred T_(I) to reduce biasing costs associated with the outputtorque request in FIG. 11, which is one of the components in the totalpower loss for the particular potential transmission operating rangestate under consideration.

In one embodiment, including when a vehicle operator makes a request foran acceleration torque that is greater than the maximum deliverableoutput torque, following generation of a plurality of engine operatingpoints (N_(I) and P_(I) pairs for continuously variable modes and T_(I)for fixed gears) for each potential transmission operating range state,which engine operating points (N_(I) and P_(I) pairs for continuouslyvariable modes and T_(I) for fixed gears) each have associated with thema T_(O) Min, T_(O) Max, and total power loss values, the desiredtransmission operating range state is determined by comparing the pointsassociated with the selected engine operating points (N_(I) and P_(I)pairs for continuously variable modes and T_(I) for fixed gears) fromeach potential transmission operating state with one another, andselecting that operating range state having the least total power lossassociated with its point biased to the highest T_(O) Max value, whichcorresponds to the least value of x in FIG. 12.

In another embodiment, including when a vehicle operator makes a requestfor a deceleration torque that is less than the minimum deliverableoutput torque, following generation of a plurality of engine operatingpoints (N_(I), P_(I) pairs for continuously variable modes and T_(I) forfixed gears) for each potential transmission operating range state,which engine operating points (N_(I), P_(I) pairs for continuouslyvariable modes and T_(I) for fixed gears) each have associated with thema T_(O) Min, T_(O) Max, and total power loss values, the desiredtransmission operating range state is determined by comparing the pointsassociated with the selected engine operating points (N_(I) and P_(I)pairs for continuously variable modes and T_(I) for fixed gears) fromeach potential transmission operating state which have the least totalpower loss with one another and selecting that operating range statehaving the least total power loss associated with its point biased tohaving the lowest T_(O) Min value (corresponding to the least value of yin FIG. 12).

In one embodiment, determination of the total power loss associated withvehicle operation at a point associated with or identified by an engineoperating point (an engine operating point, as used herein, hasassociated with it an N_(I), P_(I) pair for continuously variable modes,and a T_(I) value in the case of fixed gears) in a potential operatingrange state of the transmission comprises combining operating costs, interms of energy usage (kW), which operating costs are provided basedupon factors related to vehicle drivability, fuel economy, emissions,electrical power consumption and battery life for the operating rangestate. Lower operating costs are generally associated with lower fuelconsumption at high conversion efficiencies, lower battery power usage,and lower emissions for an operating point, and take into account acurrent operating range state of the powertrain system.

Summation of all power losses (total power loss) associated withoperating at a particular point that is associated with an engineoperating point of a potential transmission operating range stateprovides a preferability factor (such as those shown in FIG. 3) foroperating at that particular point in the particular potentialtransmission operating range state under consideration. In the case whenthe operator torque request is greater than the torque deliverable bythe driveline system, the point associated with an engine operatingpoint (N_(I), P_(I) pairs for continuously variable modes and T_(I) forfixed gears) in the respective search space S or range associated with apotential transmission operating range state may be selected to bebiased to a point at which the maximum output torque (T_(O) Max) of thetransmission occurs for that potential transmission operating rangestate. Depending on the severity of the bias cost associated with theoperator torque request, the selected point may or may not be that atwhich the maximum output torque occurs. Since the point selection isbased on minimizing the total power loss where the bias cost associatedwith the output torque request is a component of, the larger the biascosts associated with the output torque request the more advantage thereis to selecting the point at which the maximum output torque of thetransmission occurs. The search space S or range for each potentialtransmission operating range state may be examined, such as byalgorithm, and the point associated with an engine operating point atwhich the maximum output torque (T_(O) Max) of the transmission isbiased to occur identified for each potential transmission operatingrange state. The points associated with the engine operating point atwhich the maximum output torque (T_(O) Max) of the transmission isbiased to occur for each potential transmission operating range stateare compared with one another to identify the potential transmissionoperating range state having the lowest power loss that is likely tohave the highest T_(O) Max, which potential transmission operating rangestate is selected as being the preferred transmission operating rangestate when a vehicle operator makes a request for an accelerationtorque, which is a torque request that tends to deliver more torque tothe vehicle drive wheel(s) that are in contact with the road surface.

Similarly, in the case when the operator torque request is less than thetorque deliverable by the driveline system, the point associated with anengine operating point associated with a potential transmissionoperating range state may be selected to be biased to a point at whichthe minimum output torque (T_(O) Min) of the transmission occurs forthat potential transmission operating range state. Depending on theseverity of the bias cost associated with the operator torque request,the point selected may or may not be that at which the minimum outputtorque occurs. Since the point selection is based on minimizing thetotal power loss where the bias cost associated with the output torquerequest is a component of, the larger the bias costs associated with theoutput torque request the more advantage there is to selecting the pointat which the minimum output torque of the transmission occurs. Thesearch space S, or range for each potential transmission operating rangestate may be examined, such as algorithmically using a microprocessor,and the point associated with an N_(I) and P_(I) pair at which theminimum output torque (T_(O) Min) of the transmission is biased to occuridentified for each potential transmission operating range state. Thepoints associated with the engine operating point at which the minimumoutput torque (T_(O) Min) of the transmission is biased to occur foreach potential transmission operating range state are compared with oneanother to identify the potential transmission operating range statehaving the lowest total power loss which is likely to have the lowestT_(O) Min, which potential transmission operating range state isselected as being the preferred transmission operating range state whena vehicle operator makes a request for an deceleration torque, which isa torque request that tends to deliver less torque to the vehicle drivewheel(s) that are in contact with the road surface.

According to one embodiment of this disclosure, for cases of operatortorque requests which command heavy vehicle acceleration (levels ofacceleration for which the operator torque request is greater than thatdeliverable by the driveline system and the pre-determined bias costassociated with the output torque request is severe enough to overruleall other components of the total power loss), determining the engineoperating point having the least power loss associated with themautomatically results in determination of the N_(I) and P_(I) pairhaving the T_(O) Max, because the engine operating point having thehighest T_(O) Max values associated with it, also has the smallest powerlosses associated with it. The converse is true for cases of operatortorque requests which command vehicle deceleration.

Hence, in a method according to an embodiment of the disclosure, anoperator torque request is made during operation of a vehicle equippedwith a system as herein described. A search engine executed by anon-board microprocessor chooses a first engine operating point from thesearch space S or range associated with a potential transmissionoperating range state. T_(O) Max and T_(O) Min values associated withthat engine operating point in the search space S or range arecalculated. Then, the power losses associated with that engine operatingpoint in the respective search space S or range are calculated. As partof the total power loss calculation, the difference between the operatortorque request and the T_(O) Max (or T_(O) Min, as may be applicable forcases where deceleration torque is requested) is assigned a biasingcost. This process is repeated for each engine operating point in thespace S or range chosen by the search algorithm associated with thatpotential transmission operating range state, which results in a costbeing associated with each chosen engine operating point in therespective search space S or range associated with that potentialtransmission operating range state. The points having the lowest biasingcosts are inherently inclined to have the highest T_(O) Max and lowestT_(O) Min values.

Thus, a method according to the disclosure is concerned with balancingselection of a transmission operating range state from a set ofpotential transmission operating range states between choosing engineoperating point (N_(I), P_(I) pair for continuously variable modes andT_(I) for fixed gears, with emphasis on the N_(I) value, which is usedfor creating a desired transmission input profile as earlier describedherein) in the respective search space S or range which have the leastpower losses of the system associated with each potential transmissionoperating range state, which includes a bias cost that biases the pointselection to a point which has the highest T_(O) Max, (or lowest T_(O)Min). Preference in some embodiments may be given to those engineoperating point within the respective search space S or range for thevarious potential transmission operating range states which have theabsolute least total power losses, which includes large bias costsassociated with the output torque request, which in such instance ismore concerned with meeting an extreme torque request from the operator.In other embodiments, preference may be given to those engine operatingpoints (N_(I), P_(I) pairs for continuously variable modes and T_(I) forfixed gears) within the respective search space S or range for thevarious potential transmission operating range states which have theabsolute least total power losses, which include none or small biascosts associated with the output torque request, as this is an instancewherein it is desired to focus less on attempting to meet the extremetorque demand of the driver, and more on overall system efficiency. Thechoice between whether preference is given to system performance to meetthe operator extreme torque demand as closely as possible, or tomaximize the overall system efficiency is controllable by altering thefunction which determines the shape of the biasing costs curve shown inFIG. 11. When the slope of the curve defined by the function therein isselected to be steeper, more weight is given to meeting the operatortorque request that is higher or lower than the torque outputdeliverable by the driveline.

Once a method of the disclosure has been used to identify whichpotential transmission operating range state is to be selected, thetransmission input speed N_(I) that was the basis for the selection ofthat particular transmission operating range state is used as thetransmission input speed for continuously variable modes.

In a further embodiment, including a Torque Reserve, the range ofoperator torque requests over which the biasing cost function whichestablishes the Torque Reserve is variable. This is of benefit sinceincreasing the Torque Reserve reduces the tendency of the transmissionsystem to cause multiple shifting events and abrupt changes in inputspeed profiles which would otherwise occur frequently when thetransmission operating point is near the point where the maximumdeliverable output torque can be produced for the potential transmissionoperating range state. Decreasing the Torque Reserve enables the systemto operate closer to the point where the maximum deliverable outputtorque can be produced for the potential transmission operating rangestate when needed. Accordingly, varying the Torque Reserves fordifferent driving conditions enables the flexibility of weighting thepreference between improving drivability (reducing multiple transmissionshifting events and input speed stabilization), and improvingacceleration performance at high torque requests for each potentialtransmission operating range state for different driving conditions. Inone embodiment, a change in the range of operator torque requests overwhich the biasing costs function that establishes the Torque Reserveoperates is selectable by means of a tow/haul mode switch, which may beswitched manually by the operator, or automatically by the electroniccontrol module in response to an action of the operator, or byelectronically sensing the position of the accelerator pedal andappropriately processing the signal information to switch between suchmodalities. This is illustrated diagrammatically in FIG. 14, wherein theswitch permits selection of either a first Torque Reserve value (widthor span along the abscissa axis) associated with times in the operationwhen it is used for towing/hauling; a second Torque Reserve valueassociated with normal vehicle operation which does not involve towingor hauling; or a third Torque Reserve value of zero, associated withtimes in operation when the extremely high accelerator pedal position(for example, about 95% of full pedal range) indicates that TorqueReserve is not needed to increase performance to meet a torque requesthaving a relatively high magnitude. In a further embodiment, a switchalgorithm can be pre-set with differing ordering of priorities of whichTorque Reserve to select when multiple criteria are met, the choice ofwhich exact priorities and criteria are within the selection of thevehicle engineers.

The variability of the range of operator torque requests over which thebiasing cost function which establishes the Torque Reserve operates isillustrated for one embodiment by comparing the range of operator torquerequests over which the biasing cost function which establishes theTorque Reserve shown in FIG. 15, with that of FIG. 16. In FIG. 15, therange of operator torque requests over which the biasing cost functionwhich establishes the Torque Reserve operates is wider than the range ofoperator torque requests over which the biasing cost function whichestablishes the Torque Reserve operates in FIG. 16. FIG. 17 illustratesa biasing cost function in which the Torque Reserve value is zero, i.e.,there is no Torque Reserve. In one embodiment, the range of operatortorque requests over which the biasing cost function which establishesthe Torque Reserve operates for towing/hauling service is about 100Newton-meters. In one embodiment, the range of operator torque requestsover which the biasing cost function which establishes the TorqueReserve operates for non-towing/hauling service, or normal vehicleoperation, is about 50 Newton-meters. In one embodiment, the range ofoperator torque requests over which the biasing cost function whichestablishes the Torque Reserve operates for conditions when monitoredpedal position are high, is zero Newton-meters.

In a further embodiment, the range of operator torque requests overwhich the biasing cost function which establishes the Torque Reserveoperates is variable, based on the transmission output speed N_(O), andthe function used to determine the variability may be any functionselected by a vehicle engineer. In one non-limiting embodiment, thefunction is linear, of the form y=ax+b.

In a further embodiment, the range of operator torque requests overwhich the biasing cost function which establishes the Torque Reserveoperates is variable, either linear or non-linear, based on the positionof the accelerator pedal.

In a further embodiment, the range of operator torque requests overwhich the biasing cost function which establishes the Torque Reserveoperates is variable, either linear or non-linear, based on the rate ofchange of position of the accelerator pedal.

One or more biasing cost functions may be stored in computer memorydisposed on-board the motorized vehicle. In one embodiment, the functionused for providing the biasing costs associated with operator torquerequests is the same for all potential transmission operating rangestates. In another embodiment, the function used for providing thebiasing costs associated with operator torque requests is different forat least two of the potential transmission operating range statesconsidered in making a selection between which operating range statesare to be considered desirable or employed at a given time duringvehicle operation. In one embodiment of this disclosure, the functionused for providing the biasing costs associated with operator torquerequests in a transmission operating range state is considered in makinga selection of an engine operating point (especially the input speedselection in continuously variable modes) considered desirable oremployed at a given time during vehicle operation. Calculation of valuesof biasing costs based on the biasing cost function(s) and operatortorque request(s) is a routine matter and in one embodiment is carriedout in an on-board microprocessor, the results of the calculations beingstored in on-board computer memory.

It is understood that modifications are allowable within the scope ofthe disclosure. The disclosure has been described with specificreference to the preferred embodiments and modifications thereto.Further modifications and alterations may occur to others upon readingand understanding the specification. It is intended to include all suchmodifications and alterations insofar as they come within the scope ofthe disclosure.

1. Method for controlling a powertrain system in a motorized vehiclehaving an accelerator pedal and including an engine coupled to anelectro-mechanical transmission selectively operative in one of aplurality of transmission operating range states and one of a pluralityof engine states, wherein a control module performs the stepscomprising: determining a current transmission operating range state andengine state; determining at least one potential transmission operatingrange state and engine state; providing at least one operator torquerequest; determining preferability factors associated with the currenttransmission operating range state and engine state, and potentialtransmission operating range states and engine states, whereindetermining preferability factors associated with potential transmissionoperating range states includes assigning biasing costs to operatortorque requests which reside within a pre-determined range of possibleoperator torque requests for at least two of said potential transmissionoperating range states; preferentially weighting the preferabilityfactors for the current transmission operating range state and enginestate; and selectively commanding changing the transmission operatingrange state and engine state based upon said preferability factors andsaid operator torque request.
 2. The method according to claim 1 whereinsaid pre-determined range is bounded at one of the ends of said range bya torque request value that corresponds substantially to the maximumtorque output possible for a selected engine operating point at aparticular transmission operating range state under consideration. 3.The method according to claim 1 wherein said pre-determined range isbounded at one of the ends of said range by a torque request value thatcorresponds substantially to the minimum torque output possible for aselected engine operating point at a particular transmission operatingrange state under consideration.
 4. The method according to claim 1wherein the size of the pre-determined range over which biasing costsare assigned to operator torque requests is variable.
 5. The methodaccording to claim 1 wherein the size of the pre-determined range overwhich biasing costs are assigned to operator torque requests isselectively variable.
 6. The method according to claim 4 wherein thesize of the pre-determined range is dependent upon the output speed ofsaid transmission.
 7. The method according to claim 4 wherein the sizeof the pre-determined range is dependent upon the position of anaccelerator pedal.
 8. The method according to claim 4 wherein the sizeof the pre-determined range is dependent upon the rate of change of theposition of an accelerator pedal.
 9. The method according to claim 1wherein assigning biasing costs to operator torque requests which residewithin a pre-determined range of possible operator torque requestsincludes providing a function which defines the value of the biasingcosts associated with different operator torque requests within saidrange.
 10. The method according to claim 9 wherein said function islinear.
 11. The method according to claim 9 wherein said function isnon-linear.
 12. The method according to claim 9 wherein the size of thepre-determined range of operator torque requests over which saidfunction operates is dependent upon the output speed of saidtransmission.
 13. The method according to claim 9 wherein the size ofthe pre-determined range of operator torque requests over which saidfunction operates is dependent upon a position of the accelerator pedal.14. The method according to claim 9 wherein the size of thepre-determined range of operator torque requests over which saidfunction operates is dependent upon a rate of change of a position ofthe accelerator pedal.
 15. The method according to claim 9 wherein saidpre-determined range is bounded at one of the ends of said range by atorque request value for which no biasing cost value is assigned to saidoperator torque request.
 16. A method for selecting a transmissionoperating range state from a plurality of potential transmissionoperating range states in a powertrain system including an enginecoupled to an electro-mechanical transmission, a control module performsthe steps comprising: providing an operator torque request having amagnitude; providing an on-board microprocessor having a search engineexecuted thereby; selecting a first engine operating point from a searchrange space containing possible engine operating points associated witha potential transmission operating range state; calculating maximum andminimum output torques that the powertrain system is configured todeliver that are associated with said engine operating point; assigninga biasing cost to the difference between the magnitude of the operatortorque request, and the torque deliverable by said transmission less aTorque Reserve, if operating said transmission at the parameters definedby said first engine operating point over a pre-determined range ofpossible operator torque requests; summing power losses associated withoperating said vehicle transmission at the parameters defined by saidfirst engine operating point to provide a total power loss; repeatingsaid selecting, calculating, assigning and summation for a plurality ofengine operating points in said search range space, to provide a totalpower loss associated with engine operating points in said plurality;selecting at least one engine operating point from said search rangespace which has the lowest total power loss; repeating said selecting,calculating, assigning, summing, repeating and selecting for at leasttwo potential transmission operating range states; and selectivelycommanding changing the transmission operating range state based upon ascomparison of power losses associated with selected engine operatingpoints.
 17. The method according to claim 16 wherein said engineoperating point used in selectively commanding comprises thetransmission input speed associated with the point having thetransmission input speed that was used as the basis for the selection ofthe particular transmission operating range state commanded.
 18. Themethod according to claim 16 wherein biasing costs assigned aredetermined by a function which is dependent on said operator torquerequest.
 19. The method according to claim 16 wherein the size of saidpre-determined range of possible operator torque requests is selectivelyvariable.
 20. The method according to claim 16 wherein saidpre-determined range is bounded at one of the ends of said range by atorque request value for which no biasing cost value is assigned to saidoperator torque request.
 21. A system for controlling a powertrainsystem including an engine mechanically coupled to an electro-mechanicaltransmission selectively operative in one of a plurality of transmissionoperating range states and one of a plurality of engine states,comprising: a microprocessor configured to receive data and provide anoutput, said data including a first set of preferability factors, asecond set of preferability factors relating to desired operating rangestates of said transmission, a third set of preferability factorsrelating to current operating range states of said transmission, afourth set of preferability factors, said fourth set of preferabilityfactors comprising input speed trip preferability factors; a controlmodule configured to control shifting events in said transmission, saidcontrol module having inputs and outputs, wherein output from saidmicroprocessor is provided as input to said control module, said controlmodule being configured to provide said third set of preferabilityfactors to said microprocessor as an input thereto; and anelectro-mechanical transmission in effective electrical communicationwith output from said control module; said system configuredsufficiently that commanded changes of transmission operating rangestate are executed using biasing costs assigned to potential operatingrange states of said transmission based on at least one operator torquerequest, said biasing costs being determined by a biasing cost functionwhich provides a torque reserve operative over a range of operatortorque requests, wherein the size of the range of operator torquerequests is selectively variable.